The present invention relates to a fastener, and more particularly to a screw including a screw head and a related method of installation.
There are a variety of commercially available fasteners that are designed to fasten a work piece, such as a wooden board or a composite element, to a substrate, such as a subfloor, joist or other underlying support structure. In many cases, these fasteners are in the form of threaded screws including: a large, bugle-shaped head to which an installation drive attaches (for example, a Phillips or star drive screw head); a shaft that projects from the head; threads on the shaft, and a sharpened point, which centers the screw on a location, and initially pierces the board so that the screw can advance into it. These types of screws are typically drilled downward, in an orthogonal manner, into the top of a board to fasten the board to an underlying support, such as a joist. Most of the holding power of such screws come from the bugle-shaped head engaging the board.
Recently, there have been developments in construction techniques and fastener technology that attach boards to a subfloor or underlying joist with screws, but that attempt to conceal the heads of those screws. This is achieved by advancing the screws at an angle through the sides of the boards, rather than the exposed upper surface or tops of the boards, and subsequently into an underlying support structure. When boards are placed side-by-side one another, these “side angled screws” are relatively unnoticeable by an observer looking straight down at the boards. Of course, at an angled view of the board, where portions of the sides of the boards may be visible, the screw heads may be somewhat visible, but usually not overly conspicuous.
In many applications, where the aforementioned screws are drilled through the sides of the boards, they are drilled at an angle relative to the top and bottom surfaces of the boards. Accordingly, much of the holding force of the screw is applied via the shaft or body of the screw, rather than via the head of the screw, as with conventional bugle-head deck screws.
The heads of such side angled screws include a drive feature in which a tool head of a rotary tool can be inserted to rotate the screw and advance it into the board. A common type of drive feature on conventional deck screws is a six-pointed, star-shaped patterned hole. Screws including these types of drive features are usually referred to as star drive head screws. One particular type of star drive is sold under the “TORX” trade name.
Star drive screws, and in particular, TORX head screws, come in a variety of sizes. TORX head sizes are described using the capital letter “T” followed by a number. Smaller numbers correspond to smaller dimensions of the respective screw head features. Common size TORX drives for bugle-type deck screw heads include T-15 and T-25. In contrast to bugle-type deck screws, the conventional side angled screws mentioned above are much smaller in size. For example, conventional side angled screw TORX drives are size T-10. A T-10 drive measures, point-to-point, only 0.107 inches, and only has a maximum torque range of 3.7 Nm to 4.5 Nm.
Because the screw heads of side angled screws are outfitted with such a relatively small T-10 screw drive, only a relatively low amount of torque can be applied to the screws before the TORX screw drive feature is prone to stripping. This can be particularly problematic where the boards or joists into which the side angled screws are drilled are particularly dense, either from being cold or being constructed from a wood or composite that is dense. It also can be problematic where a user improperly sets their installation tool to a high torque, and ends up stripping out the head. It can further pose issues where the screws are constructed from inferior metals or by using manufacturing techniques that lack quality control.
Accordingly, there remains room for improvement to the drive features of side angled deck screws, other features of those screws and related methods of installation.